Electric treater for dispersions



Sept. 7, 1965 R. w. STENZEL ETAL 3,205,160

ELECTRIC THEATER FOR DISPERSIONS 2 Sheets-Sheet 1 Filed Oct. 16, 1962IIEJ- 4 3 000 L M- fi .xxxw.u u 000000000 m n*u e 00000000. 170 1 3x3 FJm; 00 w WW ,L w 1.. mo 2 1 3 H w IE F RD T m F 0, JW n W 0 ,Lm 3 a w a K5 2 5 fi l 2 BY THE/l? ATTORNEYS. HARE/6, KIEcH, Russau. & KERN p 1965R. w. STENZEL ETAL 3,205,160

ELECTRIC THEATER FOR DISPERSIONS Filed Oct. 16, 1962 2 Sheets-Sheet 2 020 4o 60 a0 [00 o 1o 20 so 50 .90 I00 ELECTRODE GAP ELECTRODE LENGTH AsX, of oufer e/ecfrode rad/us (inches) CHRRY-OVEP C A PRY- OVER IN VENTORS R/cHn/w W. $TNzL DELBER W. Tue/v52 BY THE/Q ATTORNEYS- HAP/W5,mac/4, PusszLLi KERN United States Patent 20 Claims. (Cl. 204-302) Thepresent application is a continuation-in-part of our copendingapplication Serial No. 64,574, filed October 24, 1960, now abandoned.

This invention relates to a more efiicient and effective electricalmethod and apparatus for treating dispersions in which small particlesare dispersed in an oil that is relatively nonconductive as comparedwith the particulate material. The dispersions may be such that most ofthe particles would settle by gravity if given sufiicient time or theymay be more permanent dispersions or emulsions from which the particleswill settle very slowly or not at all.

In known processes and equipment for electrically resolving suchdispersions great difficulty has been encountered in producing treatedoils containing only small amounts of residual dispersed material. Onlyin recent years and by use of smooth-flow treaters employingunidirectional electric fields has it been possible on some dispersionsto reduce the residual material to a few thousandths or a few hundredthsof a percent. On other dispersions reductions only to about .5-1% arepossible in older equipment. By the present invention used on the samedispersions it becomes possible to produce treated oils containing onlya small fraction of such residuals, usually one-half or one-fourth orless and often only a few parts per million. In some instances completeremoval (within the limits of accuracy of the usual analytical methods)of the dispersed phase can be achieved.

The invention contemplates an improvement in the older commercialprocess of electrically resolving oilcontinuous dispersions wherein thedispersion flows longitudinally along relatively short interelectrodetreating spaces of relatively small length-to-gap ratio between pairs ofplate electrodes or large multiple concentric cylindrical electrodeswhile there is an electric field of high voltage gradient in theinterelectrode treating spaces, the improvement being characterized byadvancing the dispersion longitudinally along a much longerinterelectrode treating space of much larger length-to-gap ratio betweenthe inner wall of a long and narrow cell forming an outer electrode anda long inner electrode near the central axis of the cell while there isbetween such outer and inner electrodes a unidirectional high-voltageelectric field acting upon the dispersed particles of the dispersions.In many commercial forms the invention contemplates division of thedispersion into a number of small streams flowing longitudinally throughrespective cellular passages of a cellular electrode each having its ownhigh-voltage inner electrode.

It has now been found that the length of the treating field insmooth-flow treaters has an unexpected effect on the treatingeffectiveness, particularly where the field is relatively narrow in alldirections transverse to the flow. Quite unexpected results have beenfound to flow from the use of relatively long cellular passagesparticularly at higher applied voltages. These results are evidenced bysubstantially less residual material in the efiluent oil, production ofhaze-free oils, substantially higher throughput capacities and lowertreating costs. Further the treaters of the invention give more stableoperation and "ice can be made much smaller than existing smooth-flowtreaters. On light oil dispersions such as petroleum distillates thathave been treated with an alkali the invention effects an improvement ofthe order of ten fold or more as compared with the older treatment,evidenced by a greater throughput while producing a treated oilcontaining about the same residual dispersed material, by a treatmentproducing a lower residue of dispersed material at about the samethroughput or in most instances by a lower residue at a very much higherthroughput.

Dispersed particles of an oil-continuous dispersion can be acted upon bya high-voltage unidirectional electric field to coalesce orelectrophorese them. Coalescence or agglomeration brings the particlestogether into larger masses that settle from the oil. Electrophoreticaction moves the particles toward one or both the electrodes along pathstherebetween and may induce deposition on one or both electrodes orcoalescence of particles migrating in such paths. The coalescing andelectrophoretic actions are influenced in part by the relative areas,curvature and the polarity of the electrodes bounding the treatingspace, the electric field being more concentrated adjacent the electrodeof small area or higher curvature. The population density of theparticles is an important factor in determining whether separation ofthe dispersed particles will proceed predominantly by coalescene oragglomeration, or by electrophoretic deposition. Where the populationdensity is relatively high the action of the electric field will bepredominantly one of coalescence in situ in the oil, it the dispersedparticles are liquid, particularly as concerns the larger particles. Inthe case of dispersed solids, agglomeration in situ may also occur alongwith electrophoretic deposition. When the population density isrelatively low the electrophoretic action usually predominates in bothcases. In order to simplify the description following, the nomenclatureusually applicable to emulsions will be used but it is understood that,in the case of solids, agglomeration instead of coalescence may occur,although the electrophoretic movement of the solids will bequalitatively similar to that of the dispersed liquid particles,

The invention contemplates use of electrodes of sufficient length andsufficiently large length-to-gap ratio that the treating actions will bepredominantly by coalescence and electrophoresis in successive sectionsof the interelectrode space under the field patterns present in the oneor more cells employed. Stated in other words the invention contemplaesan initial predominantly coalescing or agglomerating treatment within orahead of a first portion of the interelectrode space followed by asubsequent predominantly electrophoretic treatment in a later portion ofthe same cell. Once the population density is reduced to a low value theelectrophoretic action is counted on to produce a clean-up treatmentthat reduces the residual amount of dispersed material to values manyfold less than with the aforesaid older commercial treaters employingparallel plate or multiple concentric cylinder electrodes. It isgenerally desirable that the electrode at which the gradient of theelectric field is lower, e.g. the outer electrode of a cell, should beof such polarity that the particles tend to migrate toward it.

Turbulence is also a factor in determining the elfectiveness ofcoalescing and electrophoretic actions. Turbulence may be a purelyhydraulic turbulence induced by flow or may .be induced by movement ofthe particles in the oil as a result of the electric field, being inthis latter respect a function of the population density. From whateversource, turbulence may aid in coalescence -by bringing particles intocontact or closer together to be coalesced by the action of the electricstress. However turbulence is detrimental in electrophoretic separationof the particles. The long electrodes of the invention damp outhydraulic turbulence in the electrophoretic section of theinterelectrode space and electrically induced turbulence in such sectionis very small because the population density is low.

From purely hydraulic considerations prior commercial treaters withparallel plate or multiple concentric cylinder electrodes do not alwaysproduce the desired results at economically desirable rates. Closespacing of such electrodes tends to damp out local circulations oreddies tending to form because of forward flow of the dispersions butonly those in planes that are parallel both to the flow direction and tothe lines of force of the electric field. Such circulations or eddiestend also to be established in planes that are parallel to the flowdirection but at right angles to the lines of force and with theaforesaid multiple concentric cylinder or parallel plate electrodesthere are no close electrode surfaces to impede the latter circulations,such circulations being in planes parallel to the electrode surfaces.The one or more cellular spaces of the invention largely damp out thelatter circulations or eddies as well as those earlier mentioned.

In vertical spaces between parallel plate or concentric cylinderelectrodes any thermal disturbances upset the desired equal velocity ofthe dispersion in all the spaces. For example a localized dilference intemperature in such laterally unrestricted spaces slows or acceleratesflow in a localized path as compared with laterally displaced paths. Asa further example, if in a treater of the older type the flow of thedispersion is switched from one tank to another tank which is at asomewhat higher temperature it will not only cause turbulence or rollingbut will tend to channel selectively into some of the treating spaces ofthe treater, causing a decreased upward flow in other treating spaces oreven a temporary down flow therein. Treatment in the one or more cellsof the invention substantially prevents this differential flow and givesa much more stable operation.

Likewise unequal hydraulic flow, thermal effects and theelectro-hy-draulic effects to be discussed tend to establish longcirculations in an upright interelectrode space, e.g. a tendency towardan upward flow adjacent one electrode from end to end thereof and acorresponding downward flow adjacent the other. Even if the upwardlyadvancing dispersion stream prevents an actual down flow the forcetending to induce it slows a localized portion of the stream adjacentone electrode and tends to establish swirling in the field. Such actionsare sometimes localized or more pronounced in one longitudinal zoneadjacent an electrode than in a laterally adjacent longi tudinal zone,tending likewise to create circulations adjacent the electrode itself.The one or more long cellular electrodes of the invention offeradditional insurance against such long or local circulations due both toincreased length of the interelectrode space and to the confinement ofthe dispersion in all lateral directions.

In the accompanying drawing FIG. 1 shows typical characteristic treatingcurves of the new and old treaters. FIG. 2 illustrates electro-hydrauliceffects in the end portions of a treating field. FIG, 3 is alongitudinal sectional view of a typical treater embodying theinvention, FIG. 4 being a cross-section taken as indicated. FIGS. 5, 6and 7 show alternative cellular patterns. FIG, 8 is a longitudinal"sectional View of an alternative treater, FIG. 9 being a cross-sectiontaken as indicated. FIGS. 10 and 11 illustrate alternative inletarrangements. FIGS 12 and 13 are graphical representations of theoperation of the invention and critical characteristics thereof.

Electro-hyd-raulic effects at the end portions of an interelectrodespace are illustrated diagrammatically in FIG. 2 in which a centralhigh-voltage electrode a is disposed between electrodes b and c that areat ground potential, the dispersion entering through e and flowingsuccessively through entrance end zone intermediate zone g and exit endzone It, the interelectrode space being composed of an entrance portionf, an intermediate portion g, and an exit portion h. The electrode a maybe considered as a cylindrical electrode between cylindrical electrodesb and 0, these electrodes being considered as shown in section, or theelectrode a may be considered as a rod between opposite sections b and cof a tubular electrode of circular or other cross-section.

The field pattern of the high-voltage electric field is necessarilydifferent in end zones f and h and portions f and h as compared with theintermediate zone of portion g and g, due to the edge effects in theformer which concentrate the field near edges or ends of an electrode.Considering electrical phenomena alone, the dispersion issuing from e,being normally of higher dielectric constant than the surroundingpartially-treated liquid, displaces the latter and is attracted into thezone of higher voltage gradient adjacent the end of a. It has been foundthat this and the sideward electric blast action from a near the endthereof tend to establish ring-like circulations 1' which in turnestablish lesser circulations j and j" within the interelectrode space.The field at the end of a coalesces some of the dispersed particles intolarger masses which settle out but the turbulence created by the field,exemplified as circulations j, j' and j", are detrimental to the desiredsmooth flow in the intermediate portion g. Such turbulence rises togreater heights in the interelectrode space as the applied voltage isincreased. These effects are superimposed on turbulence in the entranceend zone 1 due to hydraulic action alone. The resultingelectro-hydraulic turbulence is a limitation on the eifectiveness ofsmooth-flow treatment in the intermediate portion g,

The edge effect in the exit end zone h is somewhat dif ferent, beingdependent both upon the field pattern and the dispersion flowing fromthe exit end, particularly the population density, particle size andcharacter of the residual dispersed material that has not been treatedout in the intermediate portion g. It has been found that the fieldpattern at this end zone It also creates turbulence in a zone indicatedby the dots of FIG. 2 and that this turbulence extends progressivelydownward in the interelectrode space as the applied voltage and thepopulation density increases. It has been found that turbulence fromsuch electrohydraulic effects in the exit end zone can be minimized andmade much less than in existing treaters if the efiiuent oil containsonly minute amounts of residual dispersed material.

The full-line curve k of FIG. 1 is the known characteristic treatingcurve of a conventional electric treater, illustrating the effect oncarryover (the amount of residual dispersed material remaining in thetreated oil), plotted as ordinates, when the applied voltage gradient,plotted on the abscissae scale, changes, Curve k is typical of anelectric treater having multiple concentric cylindrical electrodes orparallel plate electrodes energized by a variable source ofunidirectional potential, the electrodes being spaced 3 inches apart andproviding interelectrode spaces 15 inches long, this being substantiallythe longest space-s commonly used in commercial treaters of this type.As voltage is applied to the treater, treatment progressively improveswith increased gradient to k'k but then deteriorates rapidly asindicated by the upward sweep of the curve beyond this optimum region,the curve k having a relatively narrow base near k'k'. With the samedispersion passing through a cell-and-rod system having aninterelectrode space 3 inches wide and 15 inches long, the forward flowbeing at the same rate, the characteristic treating curve will be aboutthe same but the treater will be much more stable under changingconditions of temperature, flow rates and other sources of hydraulicdisturbances.

The rise in the curve k beyond kk has heretofore been thought to be theresult of electric dispersion of the dispersed material due to theincreasing voltage gradients the ranges currently tested.

.5 adjacent one or both electrodes and no way has heretofore been foundto eliminate this rise. The present invention is based to a large extenton the discovery that by using a cellular electrode and increasing thelength of the interelectrode spaces the shape of the characteristictreating curve changes quite unexpectedly. For example, with the samecell-and-rod electrode system mentioned above and with all otherconditions the same with the exception that the interelectrode spaceswithin the cells are made 24 inches long, the characteristic treatingcurve is changed to dot-dash curve 112' which not only has a minimummuch lower than k but which usually reaches its minimum at asubstantially higher applied voltage gradient as suggested at mm.Likewise if conditions are the same and the interelectrode spaces withinthe cells are made about 40 inches long the characteristic treatingcurve will be as represented by the dot curve n which reaches an evenlower minimum at nn at an even higher applied voltage gradient.

It will be noted that the curves m and n have a much broader base thanthe curve k of the older process, evidencing that near-minimum amountsof residual material can be obtained over a wider range of appliedvoltages or voltage gradients. This is a characterizing feature of theinvention even in these instances in which the minima mm' and n'n' ofcurves like In and n are closer to or about the same as kk as is true insome instances. The same is true in starting with a dispersion of lowercontent of dispersed material which when treated in accordance with theinvention will often produce a curve indicated by circles and whichextends substantially parallel to the abscissae axis with little or norise with increasing applied voltage gradients within It will thus beseen that substantially better treatment results through use of cellularelectrodes when operated in a range considerably higher than the k-k'value.

In most instances, such for example as in the treatment of petroleumdistillates with alkaline solutions, the minima of the characteristictreating curves of conventional parallel-plate or multiple concentriccylinder commercial treaters fall in the range of 3-6 kv./ inch. Howeverwith the long cellularized electrodes of the invention the minima areoften at applied voltage gradients at least twice as high as they wouldbe with the older treaters. Since the treating forces increaseapproximately as the square of the applied voltage gradient the improvedtreatment with the cellular electrodes thus results in considerablemeasure from the higher optimum voltage gradient which can be appliedwith this system.

The curves k, m and n of FIG. 1 are all at the same forward velocity ofthe liquid in the interelectrode space. Even with substantially higherforward velocities through the longer cellularized electrodes the curvesIn and n will have minima substantially below that of curve k and atvalues of applied voltage the same as or higher than k'k'. For exampleapproximately doubling the rate of advancement along the interelectrodespace under the conditions of curve n will shift the rise of the curveonly to that approximated by the dot curve p, evidencing a many foldincrease in treating effectiveness even at higher throughputs ascompared with the older processes.

The time in the field depends on the forward velocity but it is oftenfound that treating results are better even if the time in the fieldwhen using the long cellular electrodes is less, compared with the timein the field of curve k resulting from use of conventional electrodes.To further illustrate this, a test wasmade under comparable conditionsand at optimum voltage gradients to compare the performance of (I) atreater of a type conventionally and widely employed commercially,having concentric cylinder electrodes providing an electric field incheslong and 3 inches wide, (II) a treater with a cellular arrangementhaving a field also 15 inches long and 3 inches wide, and (III) atreater with another cellular arrange- 6 merit having a field 3 incheswide but 40 inches long. The results of those particular tests were asfollows:

It can readily be seen that with 3% times greater upward velocity andabout 30% less time in the field, the longer cellular electrode producedcarryovcrs that were only /9, as much as the other arrangements, andpractically perfect from a commercial standpoint. Furthermore theefliuent from treater III was perfectly clear, whereas the others wereunsatisfactorily cloudy. This also indicates that the long cellularizedelectrodes have much greater throughput capacity and that treaters thusequipped can be made smaller and cheaper than if equipped with the oldermultiple cylinder or parallel plate electrodes, thus being commerciallyfar superior.

As another example of the highly beneficial effect produced byincreasing the electrode length, a kerosene-water stream was treated inan 8 inch cellular electrode system employed with 2 inch rods ofdiiferent length at an upward flow velocity of 30 inches/minute. With aninterelectrode treating space or rod length of 15 inches the systemproduced an oil having a carryover of 36 p.p.m. of water whereas with aninterelectrode space 48 inches long the electrode system carried overonly 0.5 p.p.m This is a dramatic improvement in efiiciency which ishighly desirable for commercial use. In addition, the first stream wasvery turbid and that from the long electrode system bright and clear.Because of consumer resistance to cloudy oils the improved commercialacceptability of the clear product is obviously a great economicadvantage to the refiner. Attempts to obtain a clear oil with theshorter 15 inch interelectrode space by reducing the rate of flow werefruitless, and even at only a 6 inch per minute vertical rise a 3 p.p.m.carryover and a cloudy oil was still obtained. This clearlydemonstrates, as did the example above, that time in the field is notthe crucial criterion for determining the effectiveness of the electrictreating system but that the electrode configuration itself must befully taken into account because of the other disturbing effects such asthe electric pumping, windage, etc.

mentioned above.

In general, the invention contemplates that each cell shall be ofsufiicient length in the flow direction to prevent the electro-hydraulicturbulence in end zones 1 and h from pervading or meeting in theinterelectrode zone g.

The interelectrode space is made long enough that the electro-hydraulicturbulence in its end portions f and h' are separated by an intermediateportion g in which the dispersion advances smoothly and in substantiallaminar flow. In these ways, and particularly at the higher ap pliedvoltage gradients between k'k' and n--n of FIG. 1 or beyond n'n', thetreatment in intermediate portion g is effective in removing so much ofthe dispersed material by coalescence and electrophoretic effects thatthe electro-hydraulic turbulence in the exit end zone It is minimizedand becomes negligible. In this connection the present invention reducesthe residual dispersed material in the efiluent oil from two to ten-foldor more as compared with prior commercial treaters. For example, ondistillate dispersions it is not uncommon to produce effluent oils of 40ppm. (parts per million) with the older electrodes and 2-10 ppm. withthe cellular electrodes of the invention under the same conditions offlow and with the same dispersion. When it is required that carryoversof less than one p.p.m. be produced and when a bright oil is requiredthe cellular system of the invention can often meet such requirementswhen it is impossible to do so with the older electrode types.

complete removal. forward velocity was increased to 52.5 inches/minuteand should have a smooth surface to avoid protuberances or projectionstransverse to the flow direction that would tend to concentrate theelectric field or destroy laminar flow. It is desirable that theelectrodes should be free of dielectric coatings so that the dispersionbridges the electrode surfaces.

Each cell is of a length that is from 2-10 times or more the length,measured in the direction of flow, of conventional electrodes used incommercial emulsion resolving processes. The cells or tubular passagesof the invention for best operation are usually of a length of about24-120 inches. Improvements become marginal as the length of theinterelectrode treating space or of the tubular electrode are increasedabove about l00-120 inches and lengths above about 120 inches are not ofpractical significance for this type of treating system.

The effect of electrode length on carryover, measured at the voltagewhich gave the lowest carryover for each system, at different forwardvelocities in the field is illustrated in FIG. 12. The results hereshown are with outer electrodes or cells of 8 inch inside diameter andinner electrodes of 1 inch external diameter used on a dispersion ofwater in kerosene produced in the water washing of a kerosene stream.Curve B shows results at a forward velocity of 30 inches/minute. It isclearly seen that complete removal of the dispersed phase is obtainedwhen the interelectrode space was about 50 inches long but that withshorter lengths increasingly higher carryovers were obtained. Curve Cillustrates the test results when the forward velocity was reduced to 20inches/minute and shows that a length of about 36 inches was sufficientto give Curve A shows the results when the indicates the much longerinterelectrode spaces required to reduce the carryover to small values.Curve A also illustrates the marginal results from increasing the lengthabove about 100 inches on this kerosene-water system.

Dispersions that are more difficulty treatable require longer cells orinterelectrode treating spaces for the low carryovers suggested in FIG.12. At forward velocities less than the 20 inch/minute of curve C itbecomes impos sible to produce zero carryovers under the conditions ofthe above runs even through the residence time in the interelectrodespace is greater. If the length of the cellular interelectrode space istoo short the time in the field becomes of no controlling significanceand even extremely long residence times will not produce the lowcarryovers evidenced by the lower portions of curve C. If the samedispersion is treated at such lower forward velocities of less than 20inches/minute in conventional treaters between concentric cylinder orparallel plate electrodes it is likewise impossible to obtain the lowcarryovers evidenced by the lower reaches of curve C.

The width or distance across each cell passage will usually range fromabout 212 inches, sometimes as high as 16 inches and even up to 1824inches in some instances. With cross-sections greater than 12-16 inchesconvection and turbulence factors often become troublecell treatersoften containing five cells or more up to several hundred. The size andnumber of cells are usually related to the size of the treater.

The inner electrodes within the cells are commonly rods of solid orhollow cross-section. The specific diameter thereof is not particularlycritical. Rods ranging in diameter from about inch to a large fractionof the Width of the passage are usable. Rods of a diameter less thanabout /2 inch are not nearly as effective in the invention and their useis not desirable if high-efficiency treatment is to be achieved. Theinner electrodes are desirably centered in the cells but smalldeviations from this central position will not destroy the effectivenessof the treatment.

In most instances the cells will be oriented vertically and the rodswill be hung centrally therein. In this way all of the rod electrodeswill be parallel with respect to the individaul cells. However otherelectrode supports can be employed and will be required if the passagesof the cellular electrode are inclined or substantially horizontal.

Interelectrode treating spaces of a lengthzgap ratio that is at least inthe range about 8: 1-3021 can be employed. In commercial practice theratio is preferably in the range of about 12:125:1.

With the treaters of the invention the forward velocity of thedispersion in the electric field within the one or more cells will be atleast several inches per minute, e.g. at least 4 inches per minute, withheavier oils such as crude oils or lubricating oils, and normally 10inches per minute or higher for lighter oils, such as gasoline andkerosene, velocities up to 50 inches per minute or more being practicalwith many of these lighter oils. These forward velocities are to becompared with maximum velocities in the neighborhood of a fraction of aninch per minute with heavier oils and about 5-6 inches per minute forthe lighter oils when treating such oils in treaters with electrodes ofconventional types. With the treaters of the invention voltage gradientsof about 630 kv./inch or more are commonly used, voltage gradientfigures expressed in kv./in. being the voltage in kilovolts between theopposed electrodes divided by the gap width therebetween in inches.

The above discussion has considered the use of circular cells withconcentric rod electrodes, but the shape of the outer electrode is notparticularly critical, and may be in the form of a square or hexagonalcross section etc. We have found that these various sections are usuallynot quite as effective as the circular ones but that the differences aresmall and can usually be quite negligible for commercial purposes. Suchsmall deficiencies can be compensated for by increasing the number ofcells used or decreasing the forward flow velocities slightly etc. Forpurposes of the graphs and illustrations given, the square or hexagonalsections can be considered as circles having the same cross sectionalarea.

With cells that are circular, square or hexagonal in cross section bestresults will be obtained when the inner and outer electrodes have a formfactor F of at least about .8 and preferably between about .8 and .98 inthe following equation:

'erally expressed as an absolute distance.

, 9 the abscissa scale showing the gap in the electrode system as apercent of the outer electrode radius. Curve A shows the relationshipbetween this gap ratio and the carryover obtained in the cell electrodesystem, which in this particular system had an outer electrode diameterof 8 inches and a length of 48 inches. The carryover was measured atthe-voltage which gave the lowest results for each inner electrodediameter. The vertical flow rate in this case was 30 inches/minute forall the tests, and the best runs gave a carryover of only a few tenthsof a part per million in the region in which the gap ratio was between40 and 80%. As the inner electrode diameter became smaller (increasinggap ratio) the carryover gradually rose until about the 95% figure itbecame quite high and therefore commercially unattractive. The reasonfor this is ascribable to the fact that for any particular voltageapplied between the electrodes the gradient at the smaller electrodebegins to become very high as its diameter gets very small. This highgradient causes dispersion of droplets from the electrode surface whichthen, because of their reduced size, can be carried through the treatingzone before they can be redeposited on the walls or recoalesced.Consequently very small electrode diameters are to be avoided and weprefer to operate with a maximum gap ratio of about 95%, and preferablyabout 85% in order to obtain maximum efficiency. Beyond the 95% ratiothe treater operation becomes erratic and undesirable from a commercialstandpoint.

On the other hand, as the inner electrode became larger, the electrodegap and the gap ratio becoming smaller, there is also an increase incarryover. At first blush'it would seem that the carryover should remainlow with increasing electrode diameter, as indicated by the dotted lineB, since the field becomes more uniform. It has been discovered howeverthat there is a critical gap distance below which the treater systemshows decreasing effectiveness in removal of the dispersed material.This critical distance depends somewhat upon the nature of the dispersedmatter. It cannot be expressed accurately as a gap ratio figure but canbe gen- We have found that a gap below about A2 inch shows disturbingeffects and we prefer gaps that are at least about one inch.

The percentage of open area represented by a cell electrode system withvarying electrode gap ratios is shown by the curve C of FIGURE 13. Itwill be obvious that in order to utilize the maximum area and thereforeobtain the highest efficiency, it is desirable to operate in theright-hand portion of the curve C.

Curve A of FIG. 13 is shown for a system which gave a very low carryoverunder best conditions at a forward velocity of 30 inches/minute. Whenthe rate was decreased to inches/minute the resulting data were plottedas shown in dotted-line curve D-D In other words, complete removal ofthe dispersed phase was possible between gap ratios of and 85 at thisrate. If the velocity is increased above inches/minute curve A is merelytransposed to higher values of carryover, generally still maintainingthis characteristic shape.

When the tests were made with all conditions identical except that thelength of electrode was 15 inches instead of 48 inches, the results ofcurve B were obtained. This shows the very real and important factorwhich the elec trode length plays in obtaining the new results of thepractice of this invention. The rapid rise of the carryover in theright-hand portion of the curves A and D-D' of FIG. 13 can be ascribedto the adverse effects of a low form factor (high local gradients at thecenter electrode) and it is therefore desirable to operate withelectrode diameter ratios in which F is as high as possible, preferablyabove 0.8, taking into account however the adverse effect of gapssmaller than /2 inch, as previously pointed out.

The attached drawing suggests various commercial embodiments. In theembodiment of FIGS. 3 and 4 an upright cylindrical container 10 forms anupright passage the cross-section of which is substantially completelyoccupied by a cellular electrode 12 disposed between upper and lowerzones 13 and 14 of the container. The cellular electrode 12 provides amultiplicity of hexagonal cells 16 arranged in close proximity each witha rod electrode 17 depending therein. The rod electrodes may besuspended from hooks 18 depending from a foraminous structure 19electrically insulated from the container 10 and connected to oneterminal of a high-voltage source of unidirectional potential 20, theother terminal being grounded and thus electrically connected to thecellular electrode 12.

The dispersion to be treated is caused to flow longitudinally alongannular treating spaces 22 within the cells around the rods, entering anend portion 23 of each cell, flowing smoothly and substantiallynonturbulently along an intermediate portion 24 and exiting adjacent anend portion 25 adjacent the exit end of each cell. The coalescingsection in which treatment is predominantly one of coalescence startsbelow the rod electrodes and occupies a part of the intermediate portion24. The

electrophoretic section is here the upper or remaining part of theintermediate portion 24 wherein treatment is predominantly the result ofelectrophoretic effects. The purified oil is withdrawn at 26.

Substantially equal increments of the incoming dispersion should enterand flow along the respective treating spaces 22. In the arrangement ofFIG. 3 the incoming dispersion in pipe 28 is divided by a manifoldsystem 29 into a plurality of substantially equal streams whichdischarge directly into the cells at positions above the lower endsthereof through open-ended pipes 30. Spreaders 31 may be mounted abovethe open ends of the respective pipes.

The streams rising in the individual cells are first subjected to theelectric and electro-hydraulic effects in and below the end portion 23wherein considerable coalescence of the dispersed particles takes placeto such an extent that the stream advancing along the intermediateportion 24 contains residual dispersed particles in substantiallydecreased population density. The high-voltage electric field in theupper section of the intermediate portion 24 acts on the smooth-flowingdispersion by electrophoretic action, this intermediate portion 24 beingsufiiciently long and the applied voltage sufficiently high that thetreated oil entering the exit portion 25 contains only very littleresidual dispersed material so that the electro-hydraulic action in theend portion 25 has sub stantially no redispersive effect and creates aminimum of turbulence. The coalesced or electrophoresed dispersed-phasematerial progressively settles through the rising streams and collectsas a body 32 from which the material is withdrawn under the control of avalve 34.

It is often advantageous to extend the cellular electrode 12 into thisbody 32, e.g. to maintain the level of the body at a position L-L abovethe lower ends of the cells. This can be accomplished by a level controldevice 35 operatively connected to the valve 34 as suggested by thedotted line 36 to maintain the bottoms of the open cells constantlysubmerged in the heavier liquid of the body 32. This liquid thus forms ahydraulic seal between adjacent cells and between the outermost cellsand any portions 38 of the interior of the container not occupied by thehexagonal cells, which portions can then be left open at top and bottom.By suitable distributor design and adjustment, it is thus possible tofeed the same amount of emulsion to each cell, thus avoiding anydifferential flows therein such as might otherwise occur because ofthermal or hydraulically induced currents in conventional cross-pipedistributor arrangements. Adequate results can be obtained under someconditions by maintaining the level at a position L'L' below the bottomsof the cells, as by associating the operative connection 36 with alower-positioned control device 35'. Flow of the ensquare cells that isoften advantageous.

tering dispersion into unoccupied portions 38 can then be avoided byextending the pipes 30 a considerable distance into the respective cellsor the tops of these unoccupied portions 38 can be blocked off.

The treaters of the invention operate best if the dispersion enteringthe entrance ends of the interelectrode spaces contains only arelatively small amount of dispersed material, usually less than about0.5%, although they are operative and give improved results overexisting treaters with dispersions having larger amounts of dispersedmaterial. In many instances improved results and economies in treaterdesign can be achieved if some of the dispersed material is firstpreliminarily separated, such as byflow through an electric treater 40which may be a When the water content of the emulsion discharging intothe cell was 7.5%, an overhead carryover of 38 p.p.m. of water occurredat the optimum voltage gradient. When the water content of the emulsionwas reduced to 0.5 the carryover was 11 p.p.m. and when reduced to 0.1%,

it was 5 p.p.m. As another example a light catalytic cycle oil mixedwith 6% strong caustic solution produced a treated oil containing 2p.p.m. carryover when advancing at a rate of 20 inches/min. in a cell 8inches square having an inner electrode 2 inches in diameter at agradient of 13.5 kv./inch. When the incoming dispersion contained onlyabout .5 dispersed material the treated oil contained only about 0.3p.p.m. at 20 or 30 kv./ inch even at a rate of 39 inches/min, thecharacteristic treating curve being similar in shape to curve of FIG. 1.

The cellular passages may be circular, oval, triangular,

square, rectangular, polygonal or arcuate in cross-section.

If rectangular, it is desirable that the longer dimension of each cellin any cross-sectional plane should not be more than about twice theshorter dimension thereof in order to block effectively the aforesaidcirculations in planes transverse to the lines of force. It is desirablethat the longest distance from the center of each passage in anycross-sectional plane thereof measured to the cell wall have a ratiobetween 1:1 and about 2.5 :1 with respect to the shortest such distance.FIG. 5 shows a pattern of Regardless of shape, the cells may be tubes ormay be a part of a builtup unit. FIG. 6 shows circular cells made oftubes in contact with each other and FIG. 7 shows such tubes withperipheries slightly spaced in which event the unoccupied spaces 38 maybe closed by headers supporting the tubes. The closely packed cells ofany of the described arrangements occupy substantially the completecross-sectional area of the container passage in which they arepositioned. Any unoccupied spaces 38 between the cells or between theoutermost cells and the container constitute cell-blanketing spacesthermally insulating the cells in which the main treatment takes place.

In the embodiments of FIGS. 8 and 9 the cells of the cellular electrode12 may have any of the previously described cross-sectional shapes, theunoccupied portions 38 being closed at the top by a header 46. Theentering dispersion here discharges at a level below the lower ends ofthe cells through a smaller number of shorter pipes 30' providingdispersion-discharging orifices respectively below Spreaders 31'. Thezone of the treater passage adjacent the pipes 30' is divided bybarriers 50 into quadrants or smaller sections which may be of sectorialor other shape, the discharge into any particular quadrant or sectionbeing channeled upward by the barriers to a particular group ofinterelectrode spaces. The barriers 50 may extend upward to the bottomsof the cells as shown or may terminate a short distance therebelow. Theinner electrodes or rods 17 in this embodiment may terminate within therespective cells or at the ends thereof or may extend a distancetherebelow. In the latter instances preliminary treating fields will beestablished between the rods and the barriers and between the rods andthe distribution system, these fields preliminarily treating thedispersion in much the same manner as the electric treater of FIG. 3.This embodiment has the advantage that a lesser number of pipes 30 canbe used but one or a plurality of these should discharge into eachquadrant or section and should be arranged in such pattern that theforward velocity in each of the cells fed by such quadrant or sectionshould be substantially equal. The treated oil is collected by a networkof pipes 51 having a large number of orifices 52 distributed across thecross-section of the treater passage. This type of collector can be usedin any of the exemplified treaters and serves better than the singleoutlet 26 of FIG. 3 to insure that the streams in all cells havesubstantially equal forward velocity.

In FIG. 10 the inner electrodes may either extend from the ends of thecells as shown or may terminate at these ends. The incoming dispersionissues downwardly from orifices provided by short pipes 30'. Here may beused a preliminary electric treater 40' of the pipeline type having acentral electrode 55 energized from a high voltage transformer 56 anddisposed within a pipe 57. In this pre-treater 40 the flow is highlyturbulent to prevent chaining-up of the particles and thusshort-circuiting of the electrodes. Consequently little if any settlingof coalesced dispersed material takes place in such a treater. Howeverthe coalesced material in this instance settles in the main treaterimmediately upon discharge from the short pipes 30'.

In FIG. 11 most of the inner electrodes 17 terminate within therespective cells but an electrode 17 near the center of a group of cellsextends downward into the quadrant or section defined by baflles A widerfield of lower intensity is thus established between the extension ofeach electrode 17 and the adjoining baflles 50", this field servinginitiallyto treat the incoming dispersion before it enters the smallercells and thus serving somewhat the same function as the treaters 40 and57. The barriers 50 may be extensions of some of the cell walls. Theforegoing statement of the invention will suggest to those skilled inthe art various changes and modifications which can be made withoutdeparting from the spirit of the invention as defined in the appendedclaims.

We claim:

1. Apparatus for electrically treating dispersions containing smallamounts of heavier material suspended in oil to remove substantially allof such heavier material therefrom, said apparatus including:

a container providing a lower entrance zone and an upper exit zonespaced from each other in an axial direction with an intermediate zonetherebetween of a height of at least about 24, a major portion of thecross-section of said intermediate zone being an electrode zone;

electrode walls forming a plurality of closely-adjoining side-by-sidecellular treating passages in said electrode zone extending in saidaxial direction having entrance and exit ends respectively communicatingwith said lower entrance zone and said upper exit zone and forming thesole communication therebetween throughout the cross-section of saidelectrode zone, said treating passages being of the same crosssectionalsize and of an upright length of at least about 24", said electrodewalls being electrically connected together and to said container;

a plurality of elongated rod-like electrodes and means for supportingsame substantially centrally in said treating passages, said last-namedmeans including means for electrically connecting said elongatedelectrodes and electrically insulating same from said electrode walls,said elongated electrodes forming with said electrode wallsinterelectrode treating spaces each of an upright length of at leastabout 24" and of substantially uniform cross-sectional area at alllevels between the entrance and exit ends thereof, the ratio betweensuch length of each interelectrode treating space and the gap betweenthe elongated electrodes and their electrode walls being at least in therange of about 8:1-30zl;

a high-voltage source of unidirectional potential connected between saidelectrode walls and said elongated electrodes for establishing in saidinterelectrode treating spaces high-voltage unidirectional electricfields of a voltage gradient of at least about 6-30 kv./inch;

means for advancing streams of said dispersion along said interelectrodetreating spaces in a direction from said entrance ends to said exit endsthereof in bridging relationship with the electrode walls and theelongated electrodes thereof, producing a treated oil substantially freeof said heavier material issuing from said exit ends into said exit zoneand producing a body of separated heavier material in the bottom of saidentrance zone; and

7 means for withdrawing said treated oil from said exit zone and saidseparated heavier material from the bottom of said entrance zone.

2. I Apparatus as defined in claim 1 in which said major portion of thecross-section of said intermediate zone con stitutes the central portionthereof, there being a minor portion of said cross-section of saidintermediate zone comprising a blanketing space between said containerand those outermost electrode walls forming the outermost of saidplurality of treating passages, said space communicating downwardly atits lower end with said entrance zone.

3. Apparatus as defined in claim 1 in which each treating passage is ofa cross-sectional width of about 2-16 inches, in which each of saidelongated electrodes is of a cross-sectional width of at least 4 inch,and in which said gap has a minimum width of A: inch.

4. Apparatus as defined in claim 1 in which each treating passage is aperipherally closed passage of such crosssectional shape that thelongest distance between the center of such passage in anycross-sectional plane thereof measured to the electrode wall thereof hasa ratio between 1:1 and about 2.5:1 with respect to the shortest suchdisance.

5. Apparatus as defined in claim 1 in which each treating passage is ofa cross-sectional shape selected from the class consisting of circular,square and hexagonal shapes, each interelectrode treating space having aform factor, defined in equation A of about .8-.98.

6. Apparatus for electrically treating dispersions containing smallamounts of heavier material suspended in oil to remove substantially allsuch heavier material therefrom, said apparatus including:

a deep grid electrode structure having an upright axis and longaxially-extending electrode walls bounding a plurality ofclosely-adjoining similarly-sized upright cellular treating passageshaving central axes that are parallel to and spaced laterally from saidupright axis with one of said central axes being substantially coaxialwith said upright axis, said electrode walls laterally bafiling eachtreating passage from laterallyadjoining treating passages, saidelectrode walls being electrically connected together, said treatingpassages extending from end to end of such deep grid electrode structureand being of substantially uniform cross-sectional area at all levelsbetween such ends,

' each treating passage being of an axial length of at least 24 inchesand of a cross-sectional width of about 2-16 inches;

a forarnin-ous framework near but spaced from one end of said deep gridelectrode, there being means for i4 electrically insulating saidframework from said deep grid electrode structure;

a plurality of vertically elongated rod electrodes each of across-sectional width of at least inch attached to and electricallyconnected to said framework extending axially into and along saidtreating passages forming interelectrode treating spaces between theouter surfaces of said elongated electrodes and the surfaces of thecorresponding passage-bounding electrode walls, each interelectrodetreating space being of an axial length of at least about 24 inches,each interelectrode treating space being of substantially uniformcross-sectional area at all levels between the ends thereof, the ratiobetween the lengths of said interelectrode treating spaces and the gapbetween the electrode walls and the outer surfaces of said elongatedelectrodes being at least in the range of about 8: 1-0311;

a high-voltage source of undirectional potential connected between saidelectrode walls and said framework for developing in said interelectrodetreating spaces high-voltage unidirectional electric fields;

flow means for advancing streams of said dispersion at substantiallyequal upward flow rates upwardly along said interelectrode treatingspaces in bridging relation with the surfaces of said electrode wallsand said elongated electrodes;

means below said deep grid electrode structure collecting andwithdrawing heavier material separating from said dispersion; and

means above said deep grid electrode structure receiving and withdrawingtreated oil from the upper ends of said treating passages.

7. Apparatus as defined in claim 6 in which said gap is of a widthbetween about /2 inch and about of the radial distance between thecenter of the corresponding treating passage and the electrode wallthereof.

8. Apparatus as defined in claim 6 in which each treating passage is ofsuch shape that the longest distance from the center of such passage inany cross-sectional plane thereof measured to the electrode wall thereofhas a ratio between 1:1 and about 2.5 :1 with respect to the shortestsuch distance measured in such plane.

9. Apparatus as defined in claim 6 in which each treating passage is ofa cross-sectional shape selected from the class consisting of acircular, square and hexagonal shapes, each interelectrode treatingspace having a form factor, defined in Equation A of about .8.98.

10. Apparatus as defined in claim 6 in which said deep grid electrodestructure comprises a plurality of tubes of substantially uniformdiameter from end to end, the walls of said tubes forming said electrodewalls, and including means for rigidifying said tubes in side-by-siderelation, the distance between the walls of adjacent tubes being lessthan the outer diameter of said tubes.

11. Apparatus as defined in claim 6 in which said upright treatingpassages are immediately adjoining, pairs of immediately-adjoiningtreating passages being separated by a single electrode walltherebetween. I

12. Apparatus as defined in claim 6 in which said flow means includesmeans for flowing said dispersion along each of said interelectrodetreating spaces at a rate of at least about 4"/min. for dispersions ofheavier oils having gravities in the range of crude oils and lubricatingoils and of at least about 10"/min. for dispersions of lighter oilshaving gravities in the range of gasoline and kerosene.

13. Apparatus as defined in claim 6 in which said means below said deepgrid electrode structure includes walls defining an entrance chamber,the lower ends of all of said treating passages opening downwardly onsaid entrance chamber, and in which said fiow means includes means forintroducing the dispersion to be treated into said entrance chamber at aplurality of positions in a horizontal plane relatively close to saidlower ends of said treating passages.

14. Apparatus as defined in claim 13 in which at least some of saidelongated electrodes provide lower end portions protruding downwardlybelow the lower ends of their corresponding treating passages, saidhigh-voltage source establishing electric fields adjacent said lower endportions electrically treating the dispersion before entry into thelower ends of said interelectrode treating spaces.

15. Apparatus for electrically treating dispersions containing smallamounts of heavier material suspended in oil to remove substantially allsuch heavier material therefrom, said apparatus including:

a deep grid electrode structure made up of electrode walls disposed atright angles to each other forming a plurality of side-by-side uprighttreating passages each of substantially square and equal cross sectionat all levels between upper and lower ends thereof, each treatingpassage being of a width of about 2l6 and of a length of at least about24", all of said electrode walls being electrically connected together;

a plurality of elongated electrodes each of a length of at least about24" and of a cross-sectional width no less than about A inch extendingaxially into and along said upright treating passages, said elongatedelectrodes being electrically connected together and forming with saidelectrode walls interelectrode treating spaces each of a length of atleast about 24", the ratio between the actual length of eachinterelectrode treating space and the gap between the elongatedelectrode and the electrode walls bounding such interelectrode treatingspace being at least in the range of about 8:1-30z1, the distance acrosssaid gap being no less than about /2;

a high-voltage source of unidirectional potential connected between saidelectrode walls and said elongated electrodes;

flow means for advancing streams of said dispersion at substantiallyequal flow rates upwardly along said interelectrode treating spaces inbridging relation with the surfaces of said electrode walls and saidelongated electrodes;

means below said deep grid electrode structure collecting andwithdrawing heavier material separating from said dispersion; and

means above said deep grid electrode structure receiving and withdrawingtreated oil from the upper ends of said treating passages.

16. An electric treater for treating dispersions having a continuousphase of oil with small amounts of dispersed particles thereinconsituting a dispersed phase to remove substantially all of suchdispersed phase material, said electric treater including incombination: a grounded tubular electrode of an axial length of about24-120 inches and a diameter of about 2-16 inches; a rod electrodeextending along the central axis of said tubular electrode andcooperating therewith in defining an annular interelectrode treatingspace of a length of about 24120 inches between entrance and exitportions thereof, said rod electrode being of a minimum diameter ofabout /2 inch, the length-to-gap ratio of said annular treating spacebeing at least in the range of about 821-30: 1, the width of saidannular treating space between the surfaces of said rod electrode andsaid tubular electrode being between about /2 inch and about 95% of theradius of said tubular electrode, means for electrically insulating saidrod electrode from said tubular electrode; a high-voltage source ofunidirectional potential electrically connected to said tubular and rodelectrodes, said source establishing a unidirectional electric field insaid treating space of a voltage gradient of about 6-30 kv./ inch; wallsdefining an entrance chamber communicating with said entrance portion ofsaid treating space adapted to collect in the bottom thereof a body ofseparated dispersed phase material separating from said dispersion insaid treating space; means for delivering a stream of the dispersion tosaid entrance chamher at a position abOv6 said body and spacedfrom theend of said rod electrode, said dispersion flowing from said positiontoward the lower end portion of said rod electrode into said entranceportion of said treating space for treatment during flow longitudinallyalong said treating space to produce a treated oil substantially free ofresidual dispersed particles issuing from said exit portion of saidtreating space; walls defining an exit chamber communicating with saidexit portion of said treating space and receiving the treated oiltherefrom; a treated-oil outlet means communicating with said exitchamber for withdrawing the treated oil therefrom; and an outlet meanscommunicating with said body in said entrance chamber for withdrawingseparated dispersed material therefrom.

17. An electric treater as defined in claim 16 in which said treatingspace has a form factor, defined in Equation A, of about .8.98.

i3. An electric treater as defined in claim 16 in which said streamdelivery means includes means for flowing said dispersion along saidinterelectrode treating space at a rate of at least about 4"/min. fordispersions of heavier oils having gravities in the range of crude oilsand lubricating oils and of at least about 10"/rnin. for dispersions oflighter oils having gravities in the range of gasoline and kerosene.

19. Apparatus for electrically treating dispersions of oil in whichparticles of a material of greater density and higher electricalconductivity are dispersed, said apparatus including: a containerproviding entrance and exit zones spaced from each other along an axis,there being an intermediate zone therebetween of an axial dimension ofat least 24 inches; a plurality of electrically-connected cells disposedside by side in said intermediate zone, each cell being of an axiallength at least 24 inches, each cell having entrance and exit portionsrespectively communicating with said entrance and exit zones, said cellsbeing of substantially equal size in width and axial length, each cellbeing of substantially uniform cross-sectional area throughout itslength; a central electrode in each cell insulated therefrom andproviding a treating space therewithin of a high length-to-gap ratiothat is at least in the range of about 8:1-30z1 and of an axial lengthof at least 24 inches, said central electrodes being electricallyconnected together; a source of high-voltage unidirectional potentialconnected between said cells and said central electrodes establishingelectric fields in said treating spaces; means for flowing separatestreams of the dispersion axially along said treating spaces from saidentrance portions to said exit portions, said last-named means includinga dispersion distributor in said entrance zone comprising a pipe networkand a plurality of short dispersion-discharge pipes corresponding innumber to said cells and having end portions respectively extending intothe entrance portions thereof; and means for withdrawing treated oilfrom said exit zone.

20. Apparatus for electrically treating dispersions of heavier materialsuspended in oil, said apparatus including: a container providing a flowpassage having upper and lower zones adapted respectively to containseparated bodies of oil and said heavier material; effluent meansrespectively opening on said bodies to withdraw oil and heavier materialtherefrom; means controlling such effluents to maintain a level of saidbody of heavier material substantially a uniform distance above thebottom of said container; a cellular electrode having a plurality ofsideby-side cells of substantially equal cross-sectional area, each cellhaving a lower entrance portion and an upper exit portion respectivelycommunicating with said lower and upper zones; means for mounting saidcellular electrode within said container with the lower ends of saidcells below said level whereby the body of heavier material forms aliquid seal separating the interiors of said cells; means forintroducing streams of the dispersion into said cells; a plurality oflong central electrodes in said cells forming with the cell wallsinterelectrode treating spaces each of a length of at least about 24",the ratio between such length of each interelectrode treating space andthe gap between the central electrode and the cell walls being at leastin the range of about 8: 1-30: 1; and a high-voltage source ofunidirectional potential connected between said cells and said centralelectrodes for establishing highvoltage unidirectional electric fieldsin said interelectrode treating spaces.

References Cited by the Examiner 2,033,137 3/36 Fisher 204188 6/36Fisher 204299 1/51 Grove 204188 3/52 Ameman 2043 02 10/5 3 Winterniute2043 02 1/54 Bates 204188 10/58 Stenzel 204299 X 7/59 Turner 2043 02FOREIGN PATENTS 3/5 8 Netherlands.

WINSTON A. DOUGLAS, Primary Examiner.

MURRAY TILLMAN, Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,205,160 September 7, 1965 Richard W, Stenzel et alcw rtified thaterror appears in the above numbered pat- It is hereby ce d LettersPatent should read as ent requiring correction and that the saicorrected below.

Column 1, line 56, for "dispersions" read H dispersion column 3, line33, for "rolling" read roiling column 7, line 48, for "difficulty" readdifficultly line 53, for "through" read though column 8, line 69, for"hexagonal" read hexagonal line 74, for "of" read to column 9, line 14,after "until insert at column 14, line 18, for "8:1-0321" read M821-3011 column 15, lines 63 and 64, for "electrode," read electrode;

Signed and sealed this 5th day of April 1966,

(SEAL) Attest:

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner ofPatents

1. APPARATUS FOR ELECTRICALLY TREATING DISPERSIONS CONTAINING SMALLAMOUNTS OF HEAVIER MATERIAL SUSPENDED IN OIL TO REMOVE SUBSTANTIALLY ALLOF SUCH HEAVIER MATERIAL THEREFROM, SAID APPARATUS INCLUDING: ACONTAINER PROVIDING A LOWER ENTRANCE ZONE AND AN UPPER EXIT ZONE SPACEDFROM EACH OTHER IN AN AXIAL DIRECTION WITH AN INTERMEDIATE ZONETHEREBETWEEN OF A HEIGHT OF AT LEAST ABOUT 24", A MAJOR PORTION OF THECROSS-SECTION OF SAID INTERMEDIATE ZONE BEING AN ELECTRODE ZONE;ELECTRODE WALLS FORMING A PLURALITY OF CLOSELY-ADJOINING SIDE-BY-SIDECELLULAR TREATING PASSAGES IN SAID ELECTRODE ZONE EXTENDING IN SAIDAXIAL DIRECTION HAVING ENTRANCE AND EXIT ENDS RESPECTIVELY COMMUNICATINGWITH SAID LOWER ENTRANCE ZONE AND SAID UPPER EXIT ZONE AND FORMING THESOLE COMMUNICATION THEREBETWEEN THROUGHOUT THE CROSS-SECTION OF SAIDELECTRODE ZONE, SAID TREATING PASSAGES BEING OF THE SAME CROSSSECTIONALSIZE AND OF AN UPRIGHT LENGTH OF AT LEAST ABOUT 24", SAID ELECTRODEWALLS BEING ELECTRICALLY CONNECTED TOGETHER AND TO SAID CONTAINER; APLURALITY OF ELONGATED ROD-LIKE ELECTRODES AND MEANS FOR SUPPORTING SAMESUBSTANTIALLY CENTRALLY IN SAID TREATING PASSAGES, SAID LAST-NAMED MEANSINCLUDING MEANS FOR ELECTRICALLY CONNECTING SAID ELONGATED ELETRODES ANDELECTRICALLY INSULATING SAME FROM SAID ELECTRODE WALLS, SAID ELONGATEDELECTRODES FORMING WITH SAID ELECTRODE WALLS INTERELECTRODE TREATINGSPACES EACH OF AN UPRIGHT LENGTH OF AT LEAST ABOUT 24" AND OFSUBSTANTIALLY UNIFORM CROSS-SECTIONAL AREA AT ALL LEVELS BETWEEN THEENTRANCE AND EXIT ENDS THEREOF, THE RATIO BETWEEN SUCH LENGTH OF EACHINTERELECTRODE TREATING SPACE AND THE GAP BETWEEN THE ELONGATEDELECTRODES AND THEIR ELECTRODE WALLS BEING AT LEAST IN THE RANGE OFABOUT 8:1-30:1; A HIGH-VOLTAGE SOURCE OF UNIDIRECTIONAL POTENTIALCONNECTED BETWEEN SAID ELECTRODE WALLS AND SAID ELONGATED ELECTRODES FORESTABLISHING IN SAID INTERELECTRODE TREATING SPACES HIGH-VOLTAGEUNIDIRECTIONAL ELECTRIC FIELDS OF A VOLTAGE GRADIENT OF AT LEAST ABOUT6-30 KV./INCH; MEANS FOR ADVANCING STREAMS OF SAID DISPERSION ALONG SAIDINTERELECTRODE TREATING SPACES IN A DIRECTION FROM SAID ENTRANCE ENDS TOSAID EXIT ENDS THEREOF IN BRIDGING RELATIONSHIP WITH THE ELECTRODE WALLSAND THE ELONGATED ELECTRODES THEREOF, PRODUCING A TREATED OILSUBSTANTIALLY FREE OF SAID HAVIER MATERIAL ISSUING FROM SAID EXIT ENDSINTO SAID EXIT ZONE AND PRODUCING A BODY OF SEPARATED HEAVIER MATERIALIN THE BOTTOM OF SAID ENTRANCE ZONE; AND MEANS FOR WITHDRAWING SAIDTREATED OIL FROM SAID EXIT ZONE AND SAID SEPARATED HEAVIER MATERIAL FROMTHE BOTTOM OF SAID ENTRANCE ZONE.